Conventional fire sprinkler systems are used widely in factories and commercial properties, and increasingly in homes, as an active fire protection measure. A conventional sprinkler system typically includes a network of sprinkler outlets located overhead a protected area, connected to a water supply. The sprinkler outlets are maintained in a closed position until activated. Activation is usually by way of a heat-sensitive element within one or more sprinklers, which react to an ambient temperature exceeding an activation temperature. Above the activation temperature, the sprinklers are opened and water flows from the water supply on to the protected area.
A water deluge system is designed to extinguish a fire by dispensing a large volume of water over a large hazard area, and is typically used in industrial applications. FIG. 1 is a schematic view of a typical water deluge system according to the prior art. The water deluge system, generally depicted at 10, consists of a dry side 12 and a wet side 13, separated by a deluge valve 11. The dry side 12 has a network of pipes 16 and nozzles 17 which are maintained in an open condition. The dry side 12 contains air at atmospheric pressure. The wet side 13 of the deluge system is connected to a fire main 14 or other supply at a water pressure significantly higher than atmospheric pressure.
The system, generally depicted at 10, is activated automatically by a fire alarm system 18 which controls the deluge valve 11. When the deluge valve is opened, water enters the pipe work on the dry side 12 of the deluge system and is dispensed over the hazard area via the open nozzles 17. The deluge valve 11 stays open until it is activated to close.
Deluge systems find particular application in industrial applications, and are standard in onshore and offshore installations used in the oil and gas exploration and production industry. Water deluge systems perform essential health and safety functions in oil and gas installations, and therefore must be properly maintained by keeping the deluge nozzles and associated pipe work clear of debris, corrosion and blockages to ensure that the system will work effectively when required. A poorly maintained deluge system may be unable to dispense sufficient volume of water to extinguish a fire which may of course lead to risks to life and cause damage to the assets. Many offshore water deluge systems, particularly those on platforms and installations built before the 1990's, are believed to include one or more of internal corrosion, corrosion deposits and/or marine growth, any of which may restrict water flow in the pipe work and/or block nozzles.
A typical testing regime for deluge systems for the offshore oil and gas industry includes a so-called ‘wet test’ performed regularly to meet the criteria of health and safety industry regulators. A wet test involves activating the deluge system in a test period (for example 30 minutes) and checking the deluge system for blocked or restricted nozzles. This may involve manual inspection of nozzles by operators wearing offshore survival suits, checking that flow through nozzles is as expected. One method involves placing a number of receptacles beneath specific areas of the deluge system to collect dispensed seawater. The receptacles have known opening sizes, and the volume of water collected may be compared with the expected volume for the appropriate size of opening of the receptacle.
Deluge testing also typically uses pressure sensors and pipe network fluid flow analysis software such as the software package marketed by Sunrise Systems Limited under the PIPENET™ brand. The pressure sensors are installed at various locations in the deluge system on the dry side. The software package is configured to model the specific deluge system being tested, and calculate expected fluid pressures at the locations of the sensors. When a wet test is performed, the pressure readings taken are compared with the modelled pressure values, and where discrepancies exist a problem with the flow system can be inferred.
One difficulty with the testing regimes of the prior art is that they rely on wet tests being performed each time that information is required on the condition of the deluge system. Wet tests are particularly inconvenient for the management of a facility, as they rely on large volumes of water being dispensed into operational areas, typically for a test period of around 30 minutes for each region of the facility being tested. There will generally be a requirement to protect or “bag off” sensitive equipment including any electronics which is time-consuming and can be unreliable. Personnel are liable to be exposed to the water flow and therefore must wear protective clothing which may impede their mobility and ability to perform their duties. In any event, the personnel are required to carry out their duties in wet and potentially unsafe conditions. Water exposure from wet tests can also cause corrosion problems in the facility (particularly in offshore environments).
It is therefore desirable to reduce or minimise the number of wet tests performed on a deluge system for an industrial facility. Depending on the health and safety policies which apply, a deluge system deemed to be in good condition may only need to be wet tested relatively infrequently (for example every one to two years). However, where a deluge system has a history of problems or poor test results, a health and safety regulatory body may require regular cleaning and/or wet testing of the deluge system, for example every three months. This increases the inconvenience to the operator of the facility, the expense of running the facility, and the risk to personnel and the integrity of the facility.
Furthermore, frequent wet testing is likely to exacerbate problems in the deluge system, for example by increasing corrosion of the pipe work.
It is therefore an aim and object of the invention in at least one of its aspects to provide a method and apparatus for testing a deluge system which addresses one or more of the drawbacks associated with conventional testing regimes. A further aim of the invention is to provide a method and apparatus which avoids or mitigates the requirement to perform wet testing of deluge systems. An additional aim of the invention is to provide a method and/or apparatus which is applicable to the testing of deluge systems in the offshore and/or oil and gas exploration and production industries. Further aims and objects of the invention will become apparent from reading the following description.